Jake, your last statement("An a-class that ignores the recent rule 8 modifications is technically no longer an a-cat but is allowed to race with the a-cats at most of the north american events") sounds a lot like what Hobie did for years(allowing only Hobies to race in HCA races) until the numbers of one-off, PHRF ect outgrew the Hobie Class boats in some regions and change had to occur for regattas to sustain themselves.
Now, was the A Class fleet fading away and needed this boost of development? I would say no, but sailing changed around the class. When the AC started foiling, and GB, Phantom, and NACRA all started to fly, then the class who is known as the development class for cats and really much of sailing, well it had to change as well.
Does F18 or any other class have to change like that to sustain itself? No, the A cat is a different animal, almost apples to oranges in many aspects.
Mark, I think the A class has to continually change its rules as a development class. they almost need a limited set of rules, and let the true developments start happening.
IMHO you either have the rules and live by them, or you open it up and learn what the future holds